Washing machine and a method of controlling the same

ABSTRACT

Provided are a washing machine and a method of controlling the washing machine. The method includes measuring a time required for an amount of washing water supplied to a washing tub to reach a predetermined reference amount, determining a water pressure of the washing water in accordance with the measured time, and varying a water supply time in accordance with the determined water pressure. The water supply time can be adjusted according to the water pressure, it can be prevented that the washing performance is varied whenever the wash water is varied. Thus, the washing performance can be improved regardless of the water pressure.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Korean Patent Application No.10-2009-0118525 filed on Dec. 2, 2009 in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein byreference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a washing machine and a method ofcontrolling the same, and more particularly, to a washing machine and amethod of controlling the same, which can prevent washing performancefrom varying in accordance with a water pressure at a place where thewashing machine is disposed.

2. Description of the Related Art

In general, a washing machine is a machine that removes foreignsubstances from laundry by treating the laundry.

A process for treating the laundry by the washing machine includes aprocess for washing the laundry using washing water in which detergentis dissolved, a process for rinsing the laundry by supplying the washingwater, which does not contain the detergent, from an outer side to awashing tub, and a process for removing the washing water out of thelaundry that is washed. The process for treating the laundry may furtherinclude a process for drying the laundry and a process for dischargingthe laundry after ironing the laundry. However, the process for treatingthe laundry includes a detergent mixing process, a washing process, arinsing process, and a spinning process for removing the water out ofthe laundry.

All of the detergent mixing process, washing process, rinsing process,and spinning process require a process for wetting the laundry bysupplying the washing water into the washing tub. Generally, the washingwater is supplied in a direction from a cover side toward the washingtub to wet the laundry.

However, when wetting the laundry by supplying the washing water in thedirection from the cover side toward the washing tub, it is difficult toevenly wet the laundry in the washing tub. In order to overcome thislimitation, a nozzle method for spraying high-pressured washing waterfrom the cover side using a nozzle has been proposed. The nozzle methodevenly wets the laundry by spraying the washing water to the laundrythrough a narrow water outlet. However, when spraying the washing waterthrough the nozzle, an amount of the washing water supplied into thewashing tub varies in accordance with an intensity of the pressureapplied to the nozzle and thus an amount of the washing water sprayed tothe laundry varies. That is, water pressure of a place where the washingmachine is installed is not considered.

In addition, when the water pressure of the washing water is high, thewashing water sprayed through the nozzle is not directed toward thelaundry but scattered toward an inner surface of the washing tub. Whenthe water pressure of the washing water is low, the washing water maynot be properly sprayed through the nozzle.

Accordingly, a method for constantly maintaining washing performance byadjusting an amount of the washing water sprayed from the nozzle and aspraying time considering the water pressure of the place where thewashing machine is installed is required.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a washing machine and amethod of controlling the same, which determine a time for which washingwater is sprayed into a washing tub in accordance with water pressure ofa place where the washing machine is disposed.

According to an aspect of the present invention, a method of controllinga washing machine includes measuring a time required for an amount ofwashing water supplied to a washing tub to reach a predeterminedreference amount; determining a water pressure of the washing water inaccordance with the measured time; and varying a water supply time inaccordance with the determined water pressure.

According to another aspect of the present invention, a method ofcontrolling a washing machine includes filling washing water by apredetermined reference amount; measuring a time required for thewashing water to be filled; determining water pressure of the washingwater in accordance with the measured time; determining a spraying timeof the washing water in accordance with the determined water pressure;perform a wash cycle by spraying the washing water for the determinedspraying time; and perform a rinse cycle by spraying the washing waterfor the determined spraying time.

According to still another aspect of the present invention, a washingmachine includes a memory including a reference table storing data on atime required for washing water to be filled in a washing tub by apredetermined reference amount and a water pressure determined accordingto the time; and a control unit for determining the water pressure ofthe washing water with reference to the reference table and varying aspraying time of the washing time sprayed into the washing tub inaccordance with the determined water pressure.

According to the aspects of the present invention, since the time forspraying the washing water is properly adjusted in accordance with awater pressure of the washing water supplied to the washing machine, itis possible to sufficiently wet the laundry even when the water pressureof the washing water is lowered, thereby providing a proper washingstate for the laundry.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the present invention will become moreapparent from reading the Detailed Description of the Invention whichmakes reference to the attached drawings in which:

FIG. 1 is a cross-sectional view of a washing machine according to anembodiment of the present invention;

FIG. 2 is a reference view illustrating a method of controlling thewashing machine of FIG. 1;

FIG. 3 is a reference view illustrating a control flow of the washingmachine according to an embodiment of the present invention;

FIG. 4 is a reference view illustrating an example of the spray-timetable stored in the memory;

FIG. 5 is a flowchart illustrating a method of controlling the washingmachine according to an embodiment of the present invention;

FIG. 6 is a reference view illustrating an example of a method ofdetecting a laundry load;

FIG. 7 is a reference view illustrating an example of a spraying unitformed between a cover and a case; and

FIG. 8 is a reference view illustrating a method of controlling awashing machine according to another embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

The invention is described more fully hereinafter with reference to theaccompanying drawings, in which exemplary embodiments of the inventionare shown. This invention may, however, be embodied in many differentforms and should not be construed as limited to the exemplaryembodiments set forth herein. Rather, these exemplary embodiments areprovided so that this disclosure is thorough, and will fully convey thescope of the invention to those skilled in the art. Like referencenumerals in the drawings denote like elements.

FIG. 1 is a cross-sectional view of a washing machine according to anembodiment of the present invention.

Referring to FIG. 1, a washing machine includes a cabinet 10, a topcover 200 that is disposed above the cabinet 10 and provided with alaundry loading/unloading opening which the laundry can be loaded andunloaded, a lid assembly 100 that is rotatably coupled to the top coverto open and close the laundry loading/unloading opening, and a controlpanel that provides an interface so that a user can manipulate thewashing machine.

An outer tub 31 that is hung by a supporting member 20 is disposed inthe cabinet 10 and an inner tub 35 is rotatably disposed in the outertub 31.

In the present invention, when there is no need to distinguish the outertub 31 from the inner tub 35 as different things, the inner and outertubs 35 and 31 will be referred to as “washing tub 30” hereinafter. Inthe present invention, when describing a wash cycle in which a liquiddetergent that is formed by mixing a detergent with washing water issprayed, the outer and inner tubs 31 and 35 will not be described asseparate things.

A damper 25 for absorbing shaking of the outer tub 31, which is causedby vibration that is generated during rotation of the inner tub 35, isdisposed on a lower end of the supporting member 20. A pulsator 40 forforming a rotational water stream is disposed on a bottom of the inner35.

In addition, a motor 50 that is a driving unit for rotating the innertub 35 and the pulsator 40 is disposed under the outer tub 31. The motor50 is connected to the inner tub 35 through a rotational shaft 55 torotate the inner tub 35. A clutch (not shown) for selectivelytransmitting torque of the motor 50 to the inner tub 35 and the pulsator40 may be disposed between the inner tub 35 and the pulsator 40.Accordingly, depending on the operation of the clutch, only one of theinner tube 35 and the pulsator 40 may rotate or both of the inner tube35 and the pulsator 40 may simultaneously rotate.

Meanwhile, a detergent box 15 for storing the detergent is detachablydisposed on the top cover 200. A water supply hose 70 that is connectedto an outer water source to supply washing water to the detergent box 60and a water supply valve 75 for controlling the washing water introducedthrough the water supply hose 70 are disposed. When the water supplyvalve 75 is opened and thus the washing water is supplied from the outerwater source, the washing water is directed to the detergent box 60,after which the washing water is supplied to the inner tub 35. Thewashing water that is supplied from the detergent box 60 to the innertub 35 is filled in the outer tub 31 through a plurality of water holes36 formed on the inner tub 35 and the laundry is received in the innertub 35.

Further, a drain hose 80 for draining the washing water in the outer tub31 to an external side and a drain adjusting valve 85 for controllingthe washing water that is being drained through the drain hose 80, and adrain pump 86 are provided on a lower end of the outer tub 31.

FIG. 2 is a reference view illustrating a method of controlling thewashing machine of FIG. 1.

Referring to FIG. 2, a method of controlling the washing machineaccording to an embodiment of the present invention adjust a time forspraying the washing water toward the laundry with reference to a waterpressure of the washing water introduced into the washing machine.

A method of controlling the washing machine according to an embodimentof the present invention uses a property where, as the time forintroducing a reference amount D-th of the washing water into thewashing tub 30 increases, the water pressure is reduced and, as the timefor introducing the reference amount D-th of the washing water into thewashing tub 30 is reduced, the water pressure increases.

Here, the reference amount D-th is determined depending on an amount ofthe laundry loaded in the washing tub. If a large amount of the laundryis loaded in the washing tub 30, the reference amount D-th of thewashing water introduced into the washing tub 30 increases. On the otherhand, when a small amount of the laundry is loaded in the washing tub30, the reference amount D-th of the washing water introduced into thewashing tub 30 is reduced. The reference amount D-th to the amount ofthe laundry is defined by a data file provided in the form of areference table. The reference table may be recorded in a control unit210 to be reprogrammable or may be stored in an external memory (notshown) connected to the controlled unit 210.

The control unit 210 measures time required for the amount of thewashing water introduced into the washing tub 30 to reach the referenceamount D-th and determines the water pressure of the washing waterintroduced into the washing tub 30 with reference to the measured time.The water pressure is reduced as the time required for the amount of thewashing water to reach the reference amount D-th increases. In addition,the water pressure of the washing water introduced into the washing tub30 is determined by an amount of the water supplied to the washing tub30 per a predetermined time (e.g., about 10 seconds).

When the amount of the washing water introduced into the washing tub 30reaches the reference amount D-th, the control unit 210 calculates thewater pressure of the washing water and determines the spraying time forspraying the washing water toward the laundry loaded in the washing tube30 in accordance with the calculated water pressure.

Meanwhile, the memory (not shown) further contains a spray-time tabledefining the spraying time of the washing water into the washing tub 30in accordance with the amount of the laundry.

The control unit 210 renews the time information recorded in thespray-time table with reference to the water pressure that is calculatedbased on the time required for the amount of the washing water to reachthe reference amount D-th. For example, when it is assumed that thespraying time for spraying the washing water for about 1 Kg laundry isabout 80 sec, the substantial spraying time may be 90 sec when the waterpressure is low and the spraying time recorded in the spray-time tableis renewed from about 80 sec to about 90 sec to adjust the spraying timeof the washing water toward the laundry in response to the waterpressure of the place where the washing machine is installed.

FIG. 3 is a block diagram illustrating a control flow of the washingmachine according to an embodiment of the present invention.

Referring to FIG. 3, when a user set a washing course and a washing timeby manipulating the control panel 230 after loading the laundry in thewashing tub 30, the control unit 210 determines, in accordance with thewashing course, an amount of the washing water, an amount of thedetergent, a time for rotating the washing tub 30, and a rotationalpattern. According to the determined conditions, the control unit 210supplies the detergent into the washing tub 30, after which the controlunit 210 controls a water supply driving unit 250 to primarily supplythe washing water into the washing tub 30. At this point, the amount ofthe washing water supplied to the washing tub 30 is controlled withreference to an amount detected by a sensor 220. Here, the water supplydriving unit 250 may include a water supply valve.

The memory 270 has the spray-time table that defines the time forspraying the washing water into the washing tub 30 according to theamount of the washing water and the amount of the laundry and thereference table for calculating the water pressure of the washing watersupplied through the water supply driving unit 250.

The spray-time table defines, in accordance with the amount of thelaundry loaded in the washing tub 30, an amount of the water that willbe supplied to the washing tub 30 and the time for spraying the washingwater to the washing tub 30.

The reference table indicates a table having the time required forfilling the washing tub with the washing water to the reference amountaccording to the amount of the laundry and data on the water pressure ofthe washing water or an equation for calculating the water pressure.

The control unit 210 determines the amount of the washing waterintroduced into the washing tub 30 depending on the amount of thelaundry. Hereinafter, the amount of the washing water, which isdetermined depending on the amount of the laundry, will be referred toas “reference amount.” The reference amount is determined when thelaundry is loaded in the washing tub 30.

The control unit 210 measures time required for the amount of thewashing water introduced into the washing tub 30 to reach the referenceamount and calculates the water pressure based on the measured time.When the time required for the washing water to reach the referenceamount is short, the water pressure is high. On the other hand, when thetime required for the washing water to reach the reference amount islong, the water pressure is low. The reference amount and the waterpressure data in accordance with the time required for the water amountto reach the reference amount are recorded on the reference table storedin the memory 270. The control unit determines the water pressure of thewashing water introduced through the water supply driving unit 250 withreference to the time and water pressure data that are recorded on thereference table. At this point, the control unit 210 identifies a timepoint at which the amount of the washing water reaches the referenceamount through the sensor 220 and applies the identified time point tothe water pressure calculation. Here, the reference table is recorded onthe memory 270 when a manufacturer designs and manufactures the washingmachine.

The control unit 210 determines the spraying time of the washing watersprayed into the washing tub 30 with reference to the water pressure ofthe washing water introduced into the washing tub 30 through the watersupply driving unit 250. The spraying time of the washing water isdetermined by varying the time written on the spray-time table recordedon the memory 270.

For example, when the water pressure of the washing water introducedinto the washing tub 30 is reduced by 10% and thus the time forintroducing the washing water into the washing tub 30 is retarded byabout 10%. The control unit 210 may increase the time for spraying thewashing water into the washing tub 30 by 10% in reverse proportion tothe reduction of the water pressure by 10%. At this point, the controlunit 210 may renew the spraying time written on the spray-time table byincreasing the spraying time by about 10%.

In general, when it is consumed that the water pressure of the washingwater introduced into the washing machine is constant, the control unit210 may spray the washing water into the washing tub 30 and performs thewash cycle using the renewed spray-time table.

Needless to say, when the washing machine is installed at a place wherethe water pressure frequently varies, the control unit 210 determinedthe water pressure of the washing water and renews the spray-time tablewhenever a laundry treating cycle is performed.

Next, the control unit 210 rotates the washing tub 30 or the pulsator 40by driving the IPM driver in accordance with the washing course andwashes the laundry using frictional force generated by the washing tub30 or the pulsator 40. The IPM driver is a driver for driving the motor50. The IPM driver 240 rotates the motor 50 clockwise orcounterclockwise by controlling a voltage and current applied to themotor 50.

When the control unit 210 drives the motor 50 by controlling the IPMdriver 240, the control unit 210 drives the motor 50 such that the motoralternately repeats the clockwise rotation and the counterclockwiserotation, whereby the washing tub 30 or the pulsator 40 can alternatelyrepeat the clockwise rotation and the counterclockwise rotation. As aresult, the washing efficiency can be improved.

At this point, the control unit 10 may form a rising water stream in thewashing tub 30 by rotating the washing tub 30 or the pulsator 40 andallows the washing water containing the detergent to be well mixed withthe laundry using the rising water stream.

Finally, after the wash cycle by the washing course set by the user isperformed, the control unit 210 drains the washing water that is fullyfilled in the washing tub 30 by driving the drain adjusting valve 85 andthe drain pump 86 through the drain driving unit 250 and supplies newwashing water to the washing tub 30 through the water supply drivingunit 260, after which the control unit 210 performs the spinning cyclefor the laundry using the new washing water.

FIG. 4 is a reference view illustrating an example of the spray-timetable stored in the memory.

Referring to FIG. 4, the spray-time table has 10 water amount sectionsin accordance with the amount (kg) of the laundry loaded in the washingtub 30. In each section, the amount of the laundry corresponds to thespraying time of the washing water sprayed toward the laundry.

In FIG. 4, the first water amount section is a section corresponding tothe laundry of about 0.3-1.3 kg. In addition, the spraying time of thewashing water in the first water amount section is set to be about 80seconds. If the laundry of about 1 kg is loaded in the washing tub 30,the control unit 210 sprays the washing water toward the laundry forabout 80 seconds.

The second water amount section corresponds to the laundry of about1.6-2.6 kg. Like in the first water amount section, the spraying time ofthe washing water in the second water amount section is about 80seconds. This is for simplify the algorithm by applying an identicalspraying time for the sections (e.g., the first and second water amountsections) having similar amount of the laundry. However, differentspraying times may be applied for the first and second water amountsections and the spray-time table also defines different spraying timesfor the respective water amount sections. In addition, although thewater amount sections includes the first to tenth water amount sectionsin this embodiment, the present invention is not limited to this. Forexample, the number of the water amount sections may be increased orreduced in accordance with the maximum amount of the washing water.

As described above, the control unit 210 renews the time informationrecorded on the spray-time table considering the water pressure.

When the water pressure is low, a predetermined time is added to thetime recorded on the spray-time table and the spray-time table isrenewed with the added time.

FIG. 5 is a flowchart illustrating a control method of the washingmachine according to an embodiment of the present invention.

First, the control unit 210 detects the amount of the laundry loaded inthe washing tub 30 using the rotation of the washing tub 30 or thepulsator 40. When the laundry is dry laundry that is relatively light,the control unit 201 accelerates the pulsator 40 in a direction at about200 RPM, after which the control unit 201 determines the amount of thelaundry with reference to a speed reduction time of the washing tub or aspeed reduction gradient. At this point, when the amount of the laundryloaded in the washing tub 30 is relatively small, the speed of thepulsator 40 is steeply reduced. On the other hand, when the amount ofthe laundry loaded in the washing tub 30 is relatively large, the speedof the pulsator 40 is slowly reduced.

If the laundry is wet laundry that is relatively heavy, the control unit210 accelerates the washing tub 30 instead of the pulsator 40 at about40-60 RPM, after which the control unit 210 determines the amount of thelaundry with reference to a speed reduction gradient attained when thewashing tub puts on the brakes with reserve power. (S301).

The control unit 210 may detect the amount of the laundry using the wetor dry laundry. Alternatively, the control unit 210 may detect theamount of the laundry using firstly the dry laundry and detect usingsecondly the wet laundry. When both of the method for detecting theamount of the laundry using the dry laundry and the method for detectingthe amount of the laundry using the wet laundry are used, the controlunit 210 may determines a mean value of the detected amount for the drylaundry and the detected amount for the wet laundry as the amount of thelaundry. Alternatively, when the dry laundry is detected and it isdetermined that the amount of the laundry is light, the detected amountfor the dry laundry may be determined as the amount of the laundry.Alternatively, when the detected amount for the dry laundry deviates apredetermined amount (e.g., about 6 kg), the detected amount for the wetlaundry may be determined as the amount of the laundry (S302).

Next, the control unit 210 determines the water amount section andspraying time that correspond to the amount of the laundry withreference to the spray-time table stored in the memory 270. At thispoint, the control unit 210 determines a reference amount to be suppliedto the washing tub 30. When the reference amount is determined, thecontrol unit 210 sprays the washing water into the washing tub 30through a spraying hole provided near the cover 150 by controlling thewater supply driving unit 250 (S303). Next, the control 210 determinesif the amount of the washing water sprayed into the washing tub 30reaches the reference amount (S304), measures the time required for theamount of the washing water reaches the reference amount (S305), anddetermines the water pressure of the washing water with reference to thereference table stored in the memory 270 (S306). After this, the controlunit 210 increases and reduces the spraying time recorded on thespray-time table with reference to the water pressure of the washingwater and sprays the washing water to the washing tub 30 for theincreased or reduced time.

Finally, the control unit 210 performs the remaining cycles such as thewash, rinse, and spinning cycles when the washing water sprayed towardthe laundry evenly wets the laundry (S309)

FIG. 6 is a reference view illustrating an example of a method ofdetecting a laundry load.

Referring to FIG. 6, in a laundry load table, gradient values are listedin each of laundry load sections //3, //14, //5, //6, and //7. Thelaundry load table is a table corresponding to a gradient of rotationalreduction section and a laundry load of dry laundry or wet laundry andis provided in the form of a data table in the memory 270.

In FIG. 6, the laundry load table is provided for the respective laundryload sections //3, //4, //5, //6, and //7. Gradient values (135, 129,122 . . . , and the like) corresponding to the respective laundry loadsections are written on the laundry load table. For example, if thespeed reduction gradient value of the motor 50 is about 183, it may bedetermined that the weight corresponds to the laundry load section“//4.”

Although not shown in the drawings, a weight value range of the laundrymay be assigned to each of the laundry load sections. For example, aweight value range of about 3 Kg to about 4 Kg may be assigned to thelaundry load section //3.

FIG. 7 is a reference view illustrating an example of a spraying unitformed between the cover and the case.

The washing machine of an embodiment of the present invention sprays thewashing water toward the laundry to evenly wet the laundry. The washingmachine uses a spraying unit provided in the form of a nozzle having anarrow outlet to spray the washing water.

The spraying unit 120 is a unit for spraying the circulation water intothe inner tub 31. The spraying unit 120. The spraying unit 120 has aplurality of nozzle holes (not shown) that are relatively small to spraythe washing water into the inner tub 31 through a shower manner. Sincethe spraying unit 120 directly sprays the washing water toward thelaundry loaded in the inner tub 31, it can evenly effectively wet thelaundry. This method has an advantage of reducing an amount of thewashing water that is necessary to wet the laundry as compared with atypical method where the washing water is supplied into the inner tub 31up to a predetermined water level so that the laundry can be sunk underthe washing water. Particularly, the spraying unit 120 may be set suchthat a spraying direction thereof is set toward a sidewall of the innertub 31 to effectively wet the laundry adhered to the sidewall.

FIG. 8 is s a reference view illustrating a method of controlling thewashing machine according to another embodiment of the presentinvention.

Referring to FIG. 8, the control unit 210 loads and drives a drivingpattern for each of the wash courses stored in the memory in accordancewith a wash course set by a user. The control unit 210 determines if atreatment cycle of the washing machine is a wash cycle with reference tothe driving pattern of each of the wash courses (S401). When thetreatment cycle is the wash cycle, the control unit 210 supplies thewashing water to the washing tub 30 by controlling the water supplydriving unit 250. At this point, the control unit 210 determines thewater pressure of the washing water with reference to a time for whichthe washing water is supplied to the washing tub 30 (S403). Thedetermination of the water pressure is realized with reference to areference amount and a reference table corresponding to the referenceamount, which are stored in the memory 270. After determining the waterpressure of the control unit 210, the control unit 210 stores thedetermined water pressure in the memory 270 and performs the wash cyclefor the laundry (S404).

Next, the control unit 210 determines if it is time to perform the rinsecycle for the laundry with reference to the driving pattern stored inthe memory (S405). When it is determined that it is time to perform therinse cycle for the laundry, the control unit 210 determines the timefor which the washing water will be sprayed into the washing tub 30 withreference to water pressure information stored in the memory 270 (S406)and sprays the washing water into the washing tub 30 for the determinedtime (S407).

However, the present invention is not limited to the above. For example,when the water pressure is determined, the spraying time is presetaccording to the determined water pressure and the water pressure andspraying time are stored in the memory 270, after which the waterspraying is performed in accordance with the spraying time that isstored in the spinning cycle.

Finally, the control unit 210 finishes all cycles with respect to thelaundry by spinning the washing tub 30 for the rinse and spin cycleswith respect to the laundry (S408).

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims.

1. A method of controlling a washing machine, the method comprises:measuring a time required for an amount of washing water supplied to awashing tub to reach a predetermined reference amount; determining awater pressure of the washing water in accordance with the measuredtime; and varying a water supply time in accordance with the determinedwater pressure.
 2. The method of claim 1, wherein data on a sprayingtime required for an amount of washing water to reach the predeterminedreference amount and a water pressure of the washing water are stored ina reference table in advance.
 3. The method of claim 1, in thedetermining of the present water pressure, a water pressure of washingwater supplied in the present compares with the water pressure stored inthe reference table.
 4. The method of claim 1, wherein the water supplytime is increased when the determined water pressure is less than apredetermined reference water pressure.
 5. The method of claim 1,wherein the water supply time is reduced when the determined pressure isgreater than a predetermined reference water pressure.
 6. The method ofclaim 1, wherein the water supply time is set to be in reverseproportion to the water pressure.
 7. The method of claim 1, wherein awashing water level corresponding to an amount of the laundry loaded inthe washing tub is preset, wherein the water supply time is set inaccordance with the washing water level.
 8. The method of claim 7,wherein the water supply time is set by increasing or reducing the watersupply, which is preset in accordance with the washing water level,according to variation of the determined water pressure.
 9. The methodof claim 7, wherein the water supply time set in accordance with thewashing water level varies and renewed according to the determined waterpressure.
 10. The method of claim 1, wherein the predetermined referenceamount is in proportion to an amount of the laundry loaded in thewashing tub.
 11. The method of claim 1, wherein the predeterminedreference amount is increased or reduced in accordance with a washcourse selected.
 12. A method of controlling a washing machine, themethod comprising: filling washing water by a predetermined referenceamount; measuring a time required for the washing water to be filled;determining water pressure of the washing water in accordance with themeasured time; determining a spraying time of the washing water inaccordance with the determined water pressure; perform a wash cycle byspraying the washing water for the determined spraying time; and performa rinse cycle by spraying the washing water for the determined sprayingtime.
 13. A washing machine comprises: a memory comprising a referencetable storing data on a time required for washing water to be filled ina washing tub by a predetermined reference amount and a water pressuredetermined according to the time; and a control unit for determining thepresent water pressure of the washing water with reference to thereference table and varying a spraying time of the washing time sprayedinto the washing tub in accordance with the determined water pressure.14. The washing machine of claim 13, wherein the memory furthercomprises a spray-time table storing a spraying time of the washingwater according to an amount of laundry.
 15. The washing machine ofclaim 14, wherein the control unit measures a time required for thewashing water to reach a reference amount and determines the presentwater pressure by comparing the measured time with data that is presetin the reference table.
 16. The washing machine of claim 14, wherein thecontrol unit reduces the spraying time stored in the spray-time table asthe water pressure increases.
 17. The washing machine of claim 14,wherein the control unit increases the spraying time stored in thespray-time table as the water pressure reduces
 18. The washing machineof claim 14, wherein the control unit renews the spray-time table inaccordance with the newly determined water pressure.
 19. The washingmachine of claim 14, wherein the reference amount is in proportion tothe amount of the laundry loaded in the washing tub.
 20. The washingmachine of claim 13, further comprising a water supply driving unit forsupplying the washing water for the spraying time set by the controlunit and a spraying unit for spraying the washing water into the washingtub according to operation of the water supply driving unit.